﻿using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ComTools
{
	/// <summary>
	/// CRC校验
	/// </summary>
	public class CRC
	{

		#region  CRC16
		public static byte[] CRC16(byte[] data, bool isReverse = false)
		{
			int len = data.Length;
			if (len > 0)
			{
				ushort crc = 0xFFFF;

				for (int i = 0; i < len; i++)
				{
					crc = (ushort)(crc ^ (data[i]));
					for (int j = 0; j < 8; j++)
					{
						crc = (crc & 1) != 0 ? (ushort)((crc >> 1) ^ 0xA001) : (ushort)(crc >> 1);
					}
				}
				byte hi = (byte)((crc & 0xFF00) >> 8);  //高位置
				byte lo = (byte)(crc & 0x00FF);         //低位置
				if (isReverse)
					return new byte[] { lo, hi };
				else
					return new byte[] { hi, lo };
			}
			return new byte[] { 0, 0 };
		}
		#endregion

		#region  ToCRC16
		public static string ToCRC16(string content)
		{
			return ToCRC16(content, Encoding.UTF8);
		}

		public static string ToCRC16(string content, bool isReverse)
		{
			return ToCRC16(content, Encoding.UTF8, isReverse);
		}

		public static string ToCRC16(string content, Encoding encoding)
		{
			return ByteToString(CRC16(encoding.GetBytes(content)), true);
		}

		public static string ToCRC16(string content, Encoding encoding, bool isReverse)
		{
			return ByteToString(CRC16(encoding.GetBytes(content)), isReverse);
		}

		public static string ToCRC16(byte[] data)
		{
			return ByteToString(CRC16(data), true);
		}

		public static string ToCRC16(byte[] data, bool isReverse)
		{
			return ByteToString(CRC16(data), isReverse);
		}
		#endregion

		#region  ToModbusCRC16
		public static string ToModbusCRC16(string s)
		{
			return ToModbusCRC16(s, true);
		}

		public static string ToModbusCRC16(string s, bool isReverse)
		{
			return ByteToString(CRC16(StringToHexByte(s)), isReverse);
		}

		public static string ToModbusCRC16(byte[] data)
		{
			return ToModbusCRC16(data, true);
		}

		public static string ToModbusCRC16(byte[] data, bool isReverse)
		{
			return ByteToString(CRC16(data), isReverse);
		}
		#endregion

		#region ToCRC16-CCITT-XModem
		/**
		* CRC16-XMODEM算法（四字节）
		* @param bytes
		* @return
		*/
		public static byte[] crc16_ccitt_xmodem_networkorder(byte[] bytes)
		{
			int i = crc16_ccitt_xmodem(bytes, 0, bytes.Length);
			short j = (short)i;
			byte[] rr = BitConverter.GetBytes(j);
			if (BitConverter.IsLittleEndian)
			{
				return new byte[2] { rr[1], rr[0] };
			}
			else
			{
				return rr;
			}
			//return System.Net.IPAddress.HostToNetworkOrder(j);
		}

		public static string crc16_ccitt_xmodem_networkorder(string hex)
		{
			byte[] data = StringToHexByte(hex);
			byte[] crc = crc16_ccitt_xmodem_networkorder(data);
			return BitConverter.ToString(crc).Replace("-", "");
		}

		public static string crc16_ccitt_xmodem_hostorder(string hex)
		{
			byte[] data = StringToHexByte(hex);
			byte[] crc = crc16_ccitt_xmodem_hostorder(data);
			return BitConverter.ToString(crc).Replace("-", "");
		}

		public static byte[] crc16_ccitt_xmodem_hostorder(byte[] bytes)
		{
			int i = crc16_ccitt_xmodem(bytes, 0, bytes.Length);
			short j = (short)i;
			byte[] rr = BitConverter.GetBytes(j);
			return rr;
		}

		/**
		* CRC16-XMODEM算法（四字节）
		* @param bytes
		* @param offset
		* @param count
		* @return
		*/
		public static int crc16_ccitt_xmodem(byte[] bytes, int offset, int count)
		{
			int crc = 0x0000; // initial value
			int polynomial = 0x1021; // poly value
			for (int index = offset; index < count; index++)
			{
				byte b = bytes[index];
				for (int i = 0; i < 8; i++)
				{
					bool bit = ((b >> (7 - i) & 1) == 1);
					bool c15 = ((crc >> 15 & 1) == 1);
					crc <<= 1;
					if (c15 ^ bit)
						crc ^= polynomial;
				}
			}
			crc &= 0xffff;
			return crc;
		}

		/**
		* CRC16-XMODEM算法（两字节）
		* @param bytes
		* @param offset
		* @param count
		* @return
		*/
		public static short crc16_ccitt_xmodem_short(byte[] bytes, int offset, int count)
		{
			return (short)crc16_ccitt_xmodem(bytes, offset, count);
		}
		/**
		* CRC16-XMODEM算法（两字节）
		* @param bytes
		* @param offset
		* @param count
		* @return
		*/
		public static short crc16_ccitt_xmodem_short(byte[] bytes)
		{
			return crc16_ccitt_xmodem_short(bytes, 0, bytes.Length);
		}

		#endregion

		#region  ByteToString
		public static string ByteToString(byte[] arr, bool isReverse)
		{
			try
			{
				byte hi = arr[0], lo = arr[1];
				return Convert.ToString(isReverse ? hi + lo * 0x100 : hi * 0x100 + lo, 16).ToUpper().PadLeft(4, '0');
			}
			catch (Exception ex) { throw (ex); }
		}

		public static string ByteToString(byte[] arr)
		{
			try
			{
				return ByteToString(arr, true);
			}
			catch (Exception ex) { throw (ex); }
		}
		#endregion

		#region  StringToHexString
		public static string StringToHexString(string str)
		{
			StringBuilder s = new StringBuilder();
			foreach (short c in str.ToCharArray())
			{
				s.Append(c.ToString("X4"));
			}
			return s.ToString();
		}
		#endregion

		#region  StringToHexByte
		private static string ConvertChinese(string str)
		{
			StringBuilder s = new StringBuilder();
			foreach (short c in str.ToCharArray())
			{
				if (c <= 0 || c >= 127)
				{
					s.Append(c.ToString("X4"));
				}
				else
				{
					s.Append((char)c);
				}
			}
			return s.ToString();
		}

		private static string FilterChinese(string str)
		{
			StringBuilder s = new StringBuilder();
			foreach (short c in str.ToCharArray())
			{
				if (c > 0 && c < 127)
				{
					s.Append((char)c);
				}
			}
			return s.ToString();
		}

		/// <summary>
		/// 字符串转16进制字符数组
		/// </summary>
		/// <param name="hex"></param>
		/// <returns></returns>
		public static byte[] StringToHexByte(string str)
		{
			return StringToHexByte(str, false);
		}

		/// <summary>
		/// 字符串转16进制字符数组
		/// </summary>
		/// <param name="str"></param>
		/// <param name="isFilterChinese">是否过滤掉中文字符</param>
		/// <returns></returns>
		public static byte[] StringToHexByte(string str, bool isFilterChinese)
		{
			string hex = isFilterChinese ? FilterChinese(str) : ConvertChinese(str);

			//清除所有空格
			hex = hex.Replace(" ", "").Replace("-", "");
			//若字符个数为奇数，补一个0
			hex += hex.Length % 2 != 0 ? "0" : "";

			byte[] result = new byte[hex.Length / 2];
			for (int i = 0, c = result.Length; i < c; i++)
			{
				result[i] = Convert.ToByte(hex.Substring(i * 2, 2), 16);
			}
			return result;
		}
        #endregion

        #region CRC32
        const string FOO = "-";
		private static UInt32[] Crc32Table = {
			0x00000000,0x77073096,0xEE0E612C,0x990951BA,
			0x076DC419,0x706AF48F,0xE963A535,0x9E6495A3,
			0x0EDB8832,0x79DCB8A4,0xE0D5E91E,0x97D2D988,
			0x09B64C2B,0x7EB17CBD,0xE7B82D07,0x90BF1D91,
			0x1DB71064,0x6AB020F2,0xF3B97148,0x84BE41DE,
			0x1ADAD47D,0x6DDDE4EB,0xF4D4B551,0x83D385C7,
			0x136C9856,0x646BA8C0,0xFD62F97A,0x8A65C9EC,
			0x14015C4F,0x63066CD9,0xFA0F3D63,0x8D080DF5,
			0x3B6E20C8,0x4C69105E,0xD56041E4,0xA2677172,
			0x3C03E4D1,0x4B04D447,0xD20D85FD,0xA50AB56B,
			0x35B5A8FA,0x42B2986C,0xDBBBC9D6,0xACBCF940,
			0x32D86CE3,0x45DF5C75,0xDCD60DCF,0xABD13D59,
			0x26D930AC,0x51DE003A,0xC8D75180,0xBFD06116,
			0x21B4F4B5,0x56B3C423,0xCFBA9599,0xB8BDA50F,
			0x2802B89E,0x5F058808,0xC60CD9B2,0xB10BE924,
			0x2F6F7C87,0x58684C11,0xC1611DAB,0xB6662D3D,
			0x76DC4190,0x01DB7106,0x98D220BC,0xEFD5102A,
			0x71B18589,0x06B6B51F,0x9FBFE4A5,0xE8B8D433,
			0x7807C9A2,0x0F00F934,0x9609A88E,0xE10E9818,
			0x7F6A0DBB,0x086D3D2D,0x91646C97,0xE6635C01,
			0x6B6B51F4,0x1C6C6162,0x856530D8,0xF262004E,
			0x6C0695ED,0x1B01A57B,0x8208F4C1,0xF50FC457,
			0x65B0D9C6,0x12B7E950,0x8BBEB8EA,0xFCB9887C,
			0x62DD1DDF,0x15DA2D49,0x8CD37CF3,0xFBD44C65,
			0x4DB26158,0x3AB551CE,0xA3BC0074,0xD4BB30E2,
			0x4ADFA541,0x3DD895D7,0xA4D1C46D,0xD3D6F4FB,
			0x4369E96A,0x346ED9FC,0xAD678846,0xDA60B8D0,
			0x44042D73,0x33031DE5,0xAA0A4C5F,0xDD0D7CC9,
			0x5005713C,0x270241AA,0xBE0B1010,0xC90C2086,
			0x5768B525,0x206F85B3,0xB966D409,0xCE61E49F,
			0x5EDEF90E,0x29D9C998,0xB0D09822,0xC7D7A8B4,
			0x59B33D17,0x2EB40D81,0xB7BD5C3B,0xC0BA6CAD,
			0xEDB88320,0x9ABFB3B6,0x03B6E20C,0x74B1D29A,
			0xEAD54739,0x9DD277AF,0x04DB2615,0x73DC1683,
			0xE3630B12,0x94643B84,0x0D6D6A3E,0x7A6A5AA8,
			0xE40ECF0B,0x9309FF9D,0x0A00AE27,0x7D079EB1,
			0xF00F9344,0x8708A3D2,0x1E01F268,0x6906C2FE,
			0xF762575D,0x806567CB,0x196C3671,0x6E6B06E7,
			0xFED41B76,0x89D32BE0,0x10DA7A5A,0x67DD4ACC,
			0xF9B9DF6F,0x8EBEEFF9,0x17B7BE43,0x60B08ED5,
			0xD6D6A3E8,0xA1D1937E,0x38D8C2C4,0x4FDFF252,
			0xD1BB67F1,0xA6BC5767,0x3FB506DD,0x48B2364B,
			0xD80D2BDA,0xAF0A1B4C,0x36034AF6,0x41047A60,
			0xDF60EFC3,0xA867DF55,0x316E8EEF,0x4669BE79,
			0xCB61B38C,0xBC66831A,0x256FD2A0,0x5268E236,
			0xCC0C7795,0xBB0B4703,0x220216B9,0x5505262F,
			0xC5BA3BBE,0xB2BD0B28,0x2BB45A92,0x5CB36A04,
			0xC2D7FFA7,0xB5D0CF31,0x2CD99E8B,0x5BDEAE1D,
			0x9B64C2B0,0xEC63F226,0x756AA39C,0x026D930A,
			0x9C0906A9,0xEB0E363F,0x72076785,0x05005713,
			0x95BF4A82,0xE2B87A14,0x7BB12BAE,0x0CB61B38,
			0x92D28E9B,0xE5D5BE0D,0x7CDCEFB7,0x0BDBDF21,
			0x86D3D2D4,0xF1D4E242,0x68DDB3F8,0x1FDA836E,
			0x81BE16CD,0xF6B9265B,0x6FB077E1,0x18B74777,
			0x88085AE6,0xFF0F6A70,0x66063BCA,0x11010B5C,
			0x8F659EFF,0xF862AE69,0x616BFFD3,0x166CCF45,
			0xA00AE278,0xD70DD2EE,0x4E048354,0x3903B3C2,
			0xA7672661,0xD06016F7,0x4969474D,0x3E6E77DB,
			0xAED16A4A,0xD9D65ADC,0x40DF0B66,0x37D83BF0,
			0xA9BCAE53,0xDEBB9EC5,0x47B2CF7F,0x30B5FFE9,
			0xBDBDF21C,0xCABAC28A,0x53B39330,0x24B4A3A6,
			0xBAD03605,0xCDD70693,0x54DE5729,0x23D967BF,
			0xB3667A2E,0xC4614AB8,0x5D681B02,0x2A6F2B94,
			0xB40BBE37,0xC30C8EA1,0x5A05DF1B,0x2D02EF8D
		};

		public static string CRC32(byte[] bin)
		{
			if (bin == null)
            {
				return string.Empty;
            }
			UInt32 crc = 0xFFFFFFFF;
			foreach (byte b in bin)
			{
				crc = ((crc >> 8) & 0x00FFFFFF) ^ Crc32Table[(crc ^ b) & 0xFF];
			}
			crc = crc ^ 0xFFFFFFFF;
			return crc.ToString("X").PadLeft(8,'0');
		}

		/// <summary>
		/// 获取文件的CRC32标识
		/// </summary>
		/// <param name="filePath"></param>
		/// <returns></returns>
		public static string GetFileCRC32(String filePath)
		{
			if (string.IsNullOrEmpty(filePath))
			{
				return FOO;
			}
			if (!File.Exists(filePath))
			{
				return FOO;
			}

			// 最大50M
			const int MAX_SIZE = 50 * 1024 * 1024;
			var f = new FileInfo(filePath);
			if (f.Length >= MAX_SIZE)
			{
				return FOO;
			}

			var bin = File.ReadAllBytes(filePath);
			//
			return CRC32(bin);
		}

        #endregion 
    }

}